Process of cracking oils



Dec. 29, 1931. c. P. DUBBS I PROCESS OF CRACKING OILS Original Filed Oct. 18, 1920 Patented Dec. 29, 1931 UNITED STATES PATENT .OF F ICE CARBON P. DUBBS, OF WILMET'IE, ILLINOIS, ASSIGNOB TO UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION 01 SOUTH. DAKOTA PROCESS OF CRACKING OILS Application filed October 18, 1820, Serial No. 417,555. lienewed August 15, 1927.

This invention relates to improvements in I process for cracking oils and refers more particularly to a continuous process for the cracking of relatively heavy distillates, residues or crudes in such a way as to prevent vaporization of the oil while it is being passed through the heating chamber or heating tubes. The invention permits of an elongated travel of the oil through the tubes in the heating zone without carbonizing the tubes due to the fact that the oil is intermittently allowed to vaporize at predetermined intervals in its travel, and the vapors removed from the heating tubes, while the oil continues its travel through the circuit. The manner in which this is accomplished will be hereinafter more clearly set forth.

In the drawing, the single figure shows a view, partly in side elevation and partly in vertical section of any improved a paratus.

Referring in detail to the drawing, 1 designates a furnace provided with burner 2, stack 3, fire box 4. In this furnace is mounted aplurality of tubes 5, which are connected up in series to form a continuous heating coil seated within the combustion chamber of the suitable sourceof supply. The discharge side of the pump is connected by feed line 9 having a throttle valve 10. The oil passes through the first series of tubes 11, into the. lower end of an expansion chamber 12. Here the oil is permitted to vaporize and the expanded vapors pass up through the longer vertical column shown and delivered through the discharge pipe 13 into the upper end of a vapor chamber 14. The unvaporized portion of the oil returns by line 15 into the next section of tubes 16. The oil passes through the section '16 and delivers into the lower end of an auxiliary expansion chamber 17.

by vapor pipe 18 to the same vapor chamber 14.

The'unvaporized portion of the oil passes out of the lower end of the vapor chamber 17 into the next tube section 19 where it finally discharges into the lower end of the vapor chamber 14. The vapor chamber 14 is provided with the residue drawofi' line 20 having throttle valve 21. This vapor chamber also has a vapor outlet pipe 22 having throttle valve 23, which pipe 22 projects into the lower end of a dephlegmator 24. Aspaced cap member 25 is mounted above the pipe 22, the ar-' rangement being such as to permit the vapors to pass into the dephlegmator while prevent-,

ing the reflux condensate from falling back intothe pipe 22. Instead, the reflux condensate is drawn off from the bottom of the dephlegmator through the return line 26 having throttle valve 27 and leading to the charg ing line 9. The reflux condensate can in this way be continuously returned to the heating tubes. If desired, however, the reflux condensate may be drawn oil to the branch, line 28, havin throttle valve 29 and retreated elsewhere. The dephlegmator is provided with baflles 30 and with the vapor outlet pipe 31 havin throttle valve 32, which pipe leads to a con enser coil 33 seated in condenser'box 34. The coil 33 is connected to the upper end of receiver 35. This receiver 35 has pressure gauge 36, a liquid levelgauge 37, liquid d.rawoff line 38 having throttle valve 39 and gas outlet 40 having a throttle valve 41.

The process may be operated as follows: Fuel oil from the mid-continent'field may be continuously fed through the heating coil and there subjected to an oil temperature of say, 720 degs. F., and the whole system maintalned under a pressure-of 140 pounds from the heating tubes to the receiver. As the oil passes from the first section into the auxiliary expansion. chamber 12, any light vapors will be permitted to escape and pass into the va-' por chamber while the main body of the oil still in liquid phase is returned to the next section of the tubes. Likewise it passes over the next section to the second auxiliary expansion chamber, where some vaporization. may take place, the vapors passed to the main expansion chamber 14 and the oil in liquid phase .returned to the last section and while still in liquid phase, delivered to the expansion chamber 14. Care should be taken to maintain the oil at all times in liquid phase in the tubesso as to prevent vaporization and consequent precipitation of carbon in these tubes.

It is to be understood, of course, that the principal vaporization takes place in the chamber 14 and the object of the auxiliary expansion chambers is merely to permit such light vapors as there may be a tendency to form to escape out of the heating element. It is well known to those skilled in the art that the temperature to Which the oil can be subjected and still kept in liquid phase in the tubes not only depends on the pressure and the length of the tubes but varies widely with the character of the oil treated. But anyone skilled in the art should have no difii- .culty in adjusting the temperatures to meet process. a

the above requirements.

vThe reflux condensate is preferably continuously returned to the system and subjected to further treatment while the lightest vapors pass into the receiver.

I claim as my invention:

1; A continuous process for cracking hydrocarbon oil, consisting in heating the oil to a cracking temperature while flowing in a conduit of restricted cross section, in collecting pools of oil at spaced points in the length of said conduit, in passing vapors released from the oil in said pools to an enlarged reaction zone, in delivering the heated oil after complete passage through ,said conduit to said enlarged reaction zone, in withdrawin unvaporized residual oil from said enlarge zone Without again admitting the same to said conduit, in taking off vapors from said enlarged zone for dephlegmation, condensation and collection and in maintaining a supcratmospheric pressure on the oil undergo- 1ng conversion.

2. A continuous process for cracking hydrocarbon oil, consisting in passing the oil through an elongated conduit in which the oil is raised to a cracking temperature and from intermediate points of which conduit vapors evolved from the oil are passed to an enlarged reaction zone, in delivering the highly heated oil subsequent to its passage entirely through said elongated conduit, into said enlarged reaction zone wherein substantial'vaporization occurs and from which no unvaporized oil is permitted to return to said conduit, in passing evolved vapors from said enlarged reaction zone to a dephlegmator, in

returning reflux condensate from said de phlegmator to said elongated conduit and in maintainlng a superatmospheric vaporpres- 7 sure on the oil undergoing treatment in the CARBON P. DUBBS. 

